1. Field of the Invention
The present invention relates to an injection molding machine, and more particularly, to an injection molding machine provided with an anti-vibration structure for an electric power panel.
2. Description of the Related Art
As shown in FIG. 11, an injection molding machine M has such a structure that a mold clamping mechanism section Mc and an injection mechanism section Mi are mounted on a base Mb and an electric power panel is accommodated in the base Mb. The electric power panel accommodated and secured in the base Mb is mounted with electrical components, such as a controller and control circuit of the injection molding machine M.
The injection molding machine M is designed to mass-produce molded products and requires reduction of the molding cycle time to improve productivity. In general, the cycle time is reduced by increasing the speed of a motor to achieve high acceleration-deceleration response. If mold opening/closing operation or resin injection operation is quickly performed with high response, therefore, vibration occurs in a mold opening/closing direction.
Japanese Patent Application Laid-Open No. 5-318274 discloses a system in which electrical components, such as a controller and control circuits of an injection molding machine, are mounted on an integral electric power panel and accommodated and secured in a base of the injection molding machine. This electric power panel comprises a duct section and a floorboard section, and principal electrical components are mounted on the duct section. Thus, vibrations generated in a mold clamping mechanism section and an injection mechanism section in each molding cycle are transmitted directly to the electronic components through the base and the electric power panel.
Japanese Patent Application Laid-Open No. 5-278071 discloses a structure in which an entire injection molding machine is supported by mounts that are attached to the underside of its base.
Further, Japanese Patent Application Laid-Open No. 2000-185335 discloses a structure in which electrical components of an injection molding machine are accommodated in an electric power panel, which is attached to a base of the injection molding machine with a vibration absorbing material therebetween. The vibration absorbing material, rubber, must be replaced, since it is believed to be degraded depending on or in proportion to the environmental temperature, amplitude of vibration, and repeat count and finally broken. Since the vibration absorbing material is disposed just below the electric power panel, however, it cannot be easily replaced if it is degraded and broken.
If the motor speed is increased to achieve high acceleration-deceleration response, in order to reduce the molding cycle time, vibration acceleration produced by the mold clamping mechanism section Mc and the injection mechanism section Mi increases and is transmitted to the electrical components on the electric power panel through the base Mb.
In the electrical components, including the controller and control circuits, mounted on the electric power panel, cracking of solder, loosening of connector fitting portions, etc., may occur, possibly resulting in a reduction in product life and hence breakdown, if vibration acceleration of an unallowable value repeatedly acts on the components. Accordingly, the vibration acceleration applied to the electrical components must be restricted to a predetermined value or less. If this is done, however, the motor speed and acceleration must inevitably be reduced, so that the cycle time cannot be reduced.
Vibration of the entire injection molding machine can be suppressed by replacing the mounts that support the injection molding machine with larger mounts with higher vibration absorption performance. There is a problem, however, that the larger mounts are more expensive and require larger-scale replacement work.